Rule changes demanding fishing-boat skippers and officers speak Korean are being used to keep New Zealanders out of fishing jobs, a union says.

The Merchant Service Guild - covering masters and officers on ships - says it has been trying to get its members on to foreign charter fishing boats working the exclusive economic zone. However, Immigration New Zealand (INZ) keeps changing the rules.

Its claims come after weekend news that a bill that would have outlawed slave fishing in New Zealand has failed to pass into law. This raises fears the country's international reputation for providing safe food is again at risk.

Prime Minister John Key pledged to end the abuse and make the foreign charter fishing boats fly New Zealand flags by 2016. But last week, nearly two years after the introduction of the Fisheries (Foreign Charter Vessels and Other Matters) Amendment Bill, Primary Industries Minister Nathan Guy admitted it would not get through Parliament this term.

Guild general secretary Helen McAra said the Government was worried only about reputation not exploitation.

"There is no sense of urgency on the part of the Government to push through these legislative changes," McAra said.

Since a ministerial review of the fishing industry after media exposure of the abuses, INZ had consulted the unions about work-visa applications for the fishing jobs, she said.

New Zealanders had mostly been excluded from the fishing industry since the mid-80s.

The guild had been approached over providing officers and it had told authorities it had suitably qualified New Zealand officers to man several bridges.

The guild lobbied hard but INZ kept coming up with excuses and issued visas to foreign officers and crews.

"Then next time we were approached the criteria for the jobs had been revised to include a requirement to speak Korean! And to hold a Korean maritime qualification," McAra said.

It was clear there was never any intention to give New Zealanders the jobs and instead 2500 work permits were issued a year for the charter vessels, she said.

The guild says only one foreign vessel has come under a New Zealand flag.

"We think the Government was more concerned about its reputation than the exploitation and abuse of these foreign crews working in New Zealand."